"Shadow" is the third cut off Austin's debut studio album The Secret. His performance on the morning show live from Rockefeller Plaza in New York also included his singles "Mmm Yeah" and "What About Love."

NBC says some of Austin's fans camped out overnight, and that the line ended up being several blocks long by the morning.

The 18-year-old also answered questions from correspondent Carson Daly, revealing his craziest fan encounter -- when a girl hopped into the back seat of his car while he was trying to leave a concert venue!